
const Promise = require('bluebird');
async function main(a, b, callback) {
  const arr = a + b;
  console.log('a=' + a);
  console.log('b=' + b);
  return callback(null, arr);
}
async function foo(c, d, callback) {
  const str = c - d;
  console.log('c=' + c);
  console.log('d=' + d);
  return callback(null, str);
}

async function fu(a,b) {
  const function1 = Promise.promisify(main);
  const function2 = Promise.promisify(foo);

  const data1 = await function1(a,b);
  const data2 = await function2(a,b);
  console.log(data1);
  console.log(data2);
}
fu(2,5);